JPH05322323A - Freezer device - Google Patents

Abstract

PURPOSE:To improve a freezing capability of a freezer device having a heat exchanging type accumulator by improving a utilization efficiency of an evaporator. CONSTITUTION:There is provided a heat exchanging type accumulator 5 constructed to perform a heat exchanging operation between sucked refrigerant and high pressure liquid refrigerant at an upstream side of an automatic expansion valve 3. There is provided an oil return pipe 8 having a descending gradient from the accumulator 5 to a suction pipe at an upstream side of the accumulator 5. One end of the oil return pipe 8 is opened at a target liquid surface position of the accumulator 5. The oil return pipe 8 is provided with a pilot heat exchanger 9 for use in performing a heat exchanging operation with the high pressure liquid refrigerant. A heat-sensitive cylinder 3a of the automatic expansion valve 3 is fixed to an outlet side of the pilot heat exchanger 9 of the oil return pipe 8. A degree of opening of the automatic expansion valve 3 is adjusted in such a manner that an superheating degree at the outlet port of the oil return pipe 8 is kept constant. A liquid surface position of the heat exchanging type accumulator 5 is controlled. With such an arrangement, an oil returning function is assured, the refrigerant state is properly maintained, an entire evaporator 4 can be used at a wet condition through assurance of the superheating degree so as to improve a freezing capability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a refrigeration system equipped with a heat exchange type accumulator for exchanging heat between a suction refrigerant and a high pressure liquid refrigerant.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-94-9095
As disclosed in Japanese Patent No. 8, a refrigerant circuit (x) in which a compressor (a), a condenser (b), a temperature-sensitive automatic expansion valve (c), and a liquid-filled evaporator (d) are sequentially connected. In a refrigerating apparatus including: a heat exchange configured to exchange heat between a low pressure refrigerant (a) sucked into the compressor from the evaporator (d) and a high pressure liquid refrigerant downstream of the automatic expansion valve (c). A type of low-pressure refrigerant flowing out from the evaporator (d) while the type of accumulator (e) is provided and an oil return pipe (f) is provided between the full-fill type evaporator (d) and the heat exchange type accumulator (e). A pilot heat exchanger (h) for exchanging heat between the refrigerant flowing through the pilot pipe (g) and the high-pressure liquid refrigerant at the outlet of the accumulator (e) is provided, and the pilot pipe (g) is provided. ) Pilot heat exchanger (h)
By installing the temperature-sensing cylinder (i) of the automatic expansion valve (c) on the outlet side, the refrigerating capacity is improved and the liquid-filled evaporator (d) is
A known technique is to improve the liquid level control accuracy.

That is, when the refrigeration load decreases in the evaporator (d), the liquid level of the refrigerant rises. At that time, when the amount of heat exchange with the high pressure refrigerant in the accumulator decreases, the temperature of the low pressure refrigerant, that is, the superheat And the automatic expansion valve (c) is throttled to lower the refrigerant liquid level in the evaporator. On the other hand, when the refrigeration load increases in the evaporator (d), the refrigerant liquid level decreases, but at that time, the refrigerant stops flowing through the oil return pipe (f), and the heat exchange amount of the accumulator (e) increases, so that the low pressure The degree of superheat of the refrigerant increases, the automatic expansion valve (c) opens, and the liquid level of the refrigerant in the evaporator (d) rises.
With the above operation, the liquid level of the full-fill type evaporator (d) is accurately controlled at a fixed position, and the heat exchange type accumulator (e) secures the degree of superheat, so that the evaporator (d) is to some extent. The refrigerating capacity is improved by making the state of the refrigerant to be moist.

[0004]

However, the above-mentioned conventional devices have the following problems.

That is, the refrigerant state of the full-fill type evaporator (d) can be made wet, but in order to control the liquid level, there is no choice but to have an overheated region above the evaporator (d). Since it was not obtained, and that portion did not contribute to heat exchange, there was a certain limit in improving the refrigerating capacity.

Further, even in an evaporator that is not a full-fill type evaporator as in the above-mentioned conventional example, since a region where the refrigerant vapor overheats is required near the outlet of the evaporator, the heat transfer coefficient of this portion becomes low, and However, there were certain limits in improving refrigeration capacity.

The present invention has been made in view of the above problems, and an object thereof is to control a liquid level position of a heat exchange type accumulator, not an evaporator, in a refrigerating apparatus having a heat exchange type accumulator. By ensuring the degree of superheat and using the entire evaporator in a wet state, and by returning oil from the vicinity of the liquid surface of the heat exchange type accumulator to the suction pipe, the oil return function is maintained well and the refrigeration capacity is improved. It is to improve.

[0008]

Means for Solving the Problems To achieve the above object, the means taken by the invention of claim 1 is, as shown in FIG. 1, a compressor (1), a condenser (2), a temperature sensitive tube ( A refrigerating device provided with a refrigerant circuit (7) in which a temperature-sensitive automatic expansion valve (3) additionally provided with 3a) and an evaporator (4) are sequentially connected is assumed.

A heat exchange type accumulator configured to exchange heat between the refrigerant sucked from the evaporator (4) into the compressor (1) and the high pressure liquid refrigerant upstream of the automatic expansion valve (3). (5) and one end open to the target liquid surface position of the heat exchange type accumulator (5) and the other end opens to the suction pipe on the downstream side of the heat exchange type accumulator (5) with a downward slope. And an oil return pipe (8), and pilot heat exchange for heat exchange between the refrigerant in the oil return pipe (8) and the high-pressure liquid refrigerant between the condenser (2) and the heat exchange type accumulator (5). And a container (9).

Further, the temperature-sensing automatic expansion valve (3) has a temperature-sensing cylinder (3a) arranged on the outlet side of the pilot heat exchanger (9) of the oil return pipe (8). is there.

According to a second aspect of the present invention, in the above first aspect of the invention, the evaporator (4) is a full liquid type evaporator.

The means taken by the invention of claim 3 is the pilot heat exchanger (9) according to the invention of claim 1 or 2.
Is composed of an oil return pipe (8) and an electric heater for heating the oil return pipe (8).

As shown in FIG. 2, the means taken by the invention of claim 4 is, in the invention of claim 1 or 2 described above, between the automatic expansion valve (3) and the heat exchange type accumulator (5).
A plurality of evaporators (4a) to (4c) are connected in parallel with each other.

[0014]

With the above construction, in the invention of claim 1, the refrigerant returning from the evaporator (4) to the compressor (1) exchanges heat with the high pressure liquid refrigerant in the liquid line by the heat exchange type accumulator (5). Since the superheat of the suctioned refrigerant is ensured, the evaporator (4) can be used in a wet state. Also,
Since the oil return pipe (8) opens at the target liquid surface position of the heat exchange type accumulator (5) and is connected to the suction pipe at a downward gradient, the oil having a small specific gravity and floating above the liquid refrigerant is preferential. Is returned from the oil return pipe (8) to the compressor (1), and the refrigerant flowing in the oil return pipe (8) undergoes heat exchange with the high-pressure liquid refrigerant in the pilot heat exchanger (9), whereby the refrigerant is It is surely returned to the compressor (1) in a gas state. Therefore, the oil return function is favorably ensured without causing liquid back to the compressor (1) and in addition to the fact that the evaporator (4) is used in a wet state.

At that time, the oil return pipe (8) is the heat-sensing type accumulator (5) of the automatic expansion valve (3) and the temperature sensing cylinder (3a) is the oil return pipe (8) pilot heat exchanger (9) outlet. When the liquid level of the accumulator (5) deviates from the target liquid level position as the heat exchange amount of the evaporator (4) increases or decreases, the degree of superheat of the refrigerant in the oil return pipe (8) By increasing or decreasing the opening of the automatic expansion valve (3) so as to keep the value constant, the liquid surface position is automatically controlled to match the target liquid surface position, and it is appropriate according to the change in the operating state. A stable refrigerant state is maintained.

Therefore, by the above-mentioned operation, the oil return function can be favorably maintained while properly maintaining the refrigerant state of the suction refrigerant, and the entire evaporator (4) can be used in a wet state. The refrigerating capacity will be improved.

According to the second aspect of the invention, since the liquid level is controlled on the heat exchange type accumulator (5) side, even in the case of a full-fill type evaporator, it cannot be effectively used for maintaining the liquid level in the evaporator. The heat exchange capacity of the entire evaporator (4) is effectively utilized without producing any part, and the capacity increasing action becomes remarkable.

In the third aspect of the invention, in the pilot heat exchanger (9), the oil return pipe (8) is heated by an electric heater instead of heat exchange with the high-pressure refrigerant, so that the heating amount can be controlled easily. The control state will be stabilized.

In the invention of claim 4, each evaporator (4a)-
Since it is not necessary to control the liquid level for (4c) and it is sufficient to control the liquid level for one heat exchange type accumulator (5), the circuit configuration is simplified and the manufacturing cost of the multi-type refrigerating apparatus is significantly increased. Will be reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a refrigerant piping system of a refrigerating apparatus according to the first embodiment, (1) is a compressor, (2) is a condenser,
(3) is a temperature-sensitive automatic expansion valve, (4) is a liquid-filled evaporator,
(5) is an accumulator, and the above devices are sequentially connected by a refrigerant pipe (6). That is, the refrigerant discharged from the compressor (1) is condensed in the condenser (2), then expanded by the automatic expansion valve (3), evaporated by the evaporator (4), and then cooled by the accumulator (5). A refrigerant circuit (7) configured to move the cold heat obtained in the condenser (2) to the evaporator (4) by circulating the liquid refrigerant inside and returning it to the compressor (1). Has been done.

A heat exchange coil (5b) interposed in the liquid line of the refrigerant circuit (7) is housed in the container body (5a) of the accumulator (5). 5b) is configured to perform heat exchange between the high pressure liquid refrigerant and the low pressure refrigerant sucked into the compressor (1) from the evaporator (4), and the accumulator (5) is a heat exchange type accumulator. (The suction pipe in the accumulator (5) is not shown).

Here, as a feature of the present invention, an oil return pipe (8) having a slope is provided from the heat exchange type accumulator (5) to the suction pipe on the downstream side thereof, and an inlet side end portion thereof is provided. Is configured to open at a site corresponding to the target liquid surface position of the heat exchange type accumulator (5).
Further, the oil return pipe (8) is a pilot heat exchange for exchanging heat between the refrigerant flowing through the oil return pipe (8) and the high pressure liquid refrigerant between the condenser (2) and the accumulator (5). A container (9) is provided. And oil return pipe (8)
On the outlet side of the pilot heat exchanger (9), the temperature sensing tube (3a) of the automatic expansion valve (3) is attached, and the temperature sensing tube (3a) is the pilot heat exchanger (9). The degree of superheat of the low-pressure refrigerant after heat exchange is detected, and the opening drive mechanism of the automatic expansion valve (3) is operated so as to make the degree of superheat constant.

That is, in the first embodiment, the refrigerant returning from the evaporator (4) to the compressor (1) exchanges heat with the high-pressure liquid refrigerant in the liquid line in the heat exchange type accumulator (5), thereby sucking the refrigerant. The superheat of the refrigerant is secured, and the evaporator (4) can be used in a wet state. Further, since the oil return pipe (8) opens to the target liquid surface position of the heat exchange type accumulator (5) and is connected to the suction pipe at a downward gradient, the oil having a small specific gravity and floating above the liquid refrigerant has priority. The oil is returned to the compressor (1) from the oil return pipe (8) and the evaporator (4) is used in a wet state, so that the oil return function is improved. Moreover, since heat exchange with the high-pressure liquid refrigerant is performed in the pilot heat exchanger (9) in the middle of the oil return pipe (8), even if the liquid refrigerant is mixed, it can be returned to the compressor (1) in a gas state. Thus, the oil return function can be favorably maintained without causing liquid back to the compressor (1).

At this time, the oil return pipe (8) is the heat exchange type accumulator (5), and the temperature sensing cylinder (3a) of the automatic expansion valve (3) is the outlet of the pilot heat exchanger (9) of the oil return pipe (8). The liquid level of the accumulator (5) is controlled so as to maintain the proper position by the following action. That is, when the amount of refrigerant flowing into the accumulator (5) increases due to an increase in the amount of heat exchange of the evaporator (4) and the liquid level rises from the target liquid level position, the degree of superheat of the refrigerant in the oil return pipe (8). Is decreased, the automatic expansion valve (3) is adjusted in the direction to be closed, and the amount of refrigerant flowing into the accumulator (5) is reduced to lower the liquid level, while the amount of heat exchange of the evaporator (4) is decreased. When the amount of refrigerant flowing into the accumulator (5) is reduced due to increase or the like and the liquid level is lowered, the oil return pipe (8)
Since the degree of superheat of the refrigerant increases, the automatic expansion valve (3) is adjusted in the opening direction, and the amount of refrigerant flowing into the accumulator (5) is reduced, so that the liquid level rises. By this action, the liquid surface position is automatically controlled so as to match the target liquid surface position, and in response to changes in the operating state,
It is possible to maintain an appropriate refrigerant state.

Therefore, the oil return function can be favorably maintained while properly maintaining the refrigerant state of the suction refrigerant, and
The entire evaporator (4) can be used in a wet state, and thus the refrigerating capacity can be improved.

In the first embodiment, the evaporator (4)
However, the evaporator of the present invention is not limited to the liquid-filled type. In other words, even in the dry type, there is a portion that cannot be effectively used for heat exchange in order to secure the degree of superheat, but by adopting a configuration in which the degree of superheat is secured by the heat exchange type accumulator (5), the entire evaporator is kept wet. It can be used, and the refrigerating capacity can be improved.

However, particularly in the case of a full-fill type evaporator, a region that does not contribute to heat exchange occurs above the heat exchanger in order to maintain the liquid level in the evaporator, but as in the above embodiment, the heat exchange type accumulator is used. By performing the liquid level control on the side of (5), it is possible to improve the utilization efficiency by keeping the entire evaporator (4) in a wet state, and the effect of increasing the capacity becomes remarkable.

Although not shown in the embodiment, in the pilot heat exchanger (9) of the first embodiment, the oil return pipe (8) is heated by an electric heater instead of heat exchange with the high pressure refrigerant. You may. In that case, since the control of the heating amount is easy, there is an advantage that the control state can be stabilized.

Next, a second embodiment according to the invention of claim 4 will be described. FIG. 2 shows the refrigerant piping system of the refrigeration system of the second embodiment, and the refrigerant piping system of the first embodiment (FIG. 1).
However, in the present embodiment, a plurality of liquid-filled evaporators (4a) to (4c) reduce pressure between the automatic expansion valve (3) and the heat exchange accumulator (5). The degree adjusting capillaries (10a) to (10c) are connected in parallel with each other.

In the second embodiment, it is not necessary to control the liquid level for each evaporator as in the conventional case, and it suffices to control the liquid level for one heat exchange type accumulator (5). There is an advantage that it is simplified and the manufacturing cost of the multi-type refrigerating apparatus can be significantly reduced.

[0032]

As described above, according to the invention of claim 1, as the structure of the refrigerating apparatus, the refrigerant sucked from the evaporator to the compressor by the heat exchange type accumulator and the high pressure liquid on the upstream side of the automatic expansion valve are provided. Allows heat exchange with the refrigerant, provides an oil return pipe with a downward slope between the accumulator and the suction pipe on the downstream side, and opens its inlet end at the target liquid surface position of the heat exchanger accumulator. On the other hand, a pilot heat exchanger for exchanging heat between the fluid in the oil return pipe and the high-pressure liquid refrigerant between the condenser and the heat exchange type accumulator is provided, and the temperature-sensing cylinder of the automatic expansion valve is used as the oil return pipe pilot. The structure is such that it is mounted on the outlet side of the heat exchanger, and the liquid level of the accumulator is controlled by an automatic expansion valve that operates to keep the degree of superheat of the refrigerant in the oil return pipe constant. While oil It is possible to use the evaporator in a damp state by ensuring the superheat of the refrigerant by exchanging heat with the high pressure liquid refrigerant in the heat exchange type accumulator while maintaining good function, and thus refrigerating capacity. Can be improved.

According to the invention of claim 2, since the evaporator in the invention of claim 1 is a full liquid type evaporator, liquid level control is performed on the side of the heat exchange type accumulator, so that full liquid type evaporation is performed. The utilization efficiency of the evaporator can be improved without producing a region that cannot be effectively used for maintaining the liquid level in the container, and therefore, a remarkable effect can be exhibited.

According to the invention of claim 3, in the refrigerating apparatus of claim 1 or 2, the heating of the refrigerant in the oil return pipe in the pilot heat exchanger is performed by an electric heater, so that the heating amount is controlled. Can be facilitated and the control state can be stabilized.

According to the invention of claim 4, in the refrigerating apparatus according to claim 1 or 2, the plurality of evaporators are connected in parallel between the automatic expansion valve and the heat exchange type accumulator. By controlling the liquid level of one heat exchange type accumulator without controlling the liquid level of the evaporator, the circuit configuration can be simplified.
Therefore, the manufacturing cost of the multi-type refrigeration system can be reduced.

[Brief description of drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration apparatus according to a first embodiment.

FIG. 2 is a refrigerant piping system diagram of a refrigerating apparatus according to a second embodiment.

FIG. 3 is a refrigerant piping system diagram of a conventional refrigeration system.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Automatic expansion valve 3a Temperature sensing tube 4 Evaporator 5 Heat exchange type accumulator 7 Refrigerant circuit 8 Oil return pipe 9 Pilot heat exchanger

Claims (4)

[Claims] 1. A refrigerant circuit (1) in which a compressor (1), a condenser (2), a temperature-sensitive automatic expansion valve (3) provided with a temperature-sensitive cylinder (3a), and an evaporator (4) are sequentially connected. In a refrigerating apparatus including 7), the refrigerant sucked into the compressor (1) from the evaporator (4) and the high-pressure liquid refrigerant upstream of the automatic expansion valve (3) are heat-exchanged. The heat exchange type accumulator (5) and one end open to the target liquid surface position of the heat exchange type accumulator (5) and the other end opens to the suction pipe on the downstream side of the heat exchange type accumulator (5). For exchanging heat between the oil return pipe (8) arranged with a high pressure liquid refrigerant between the refrigerant in the oil return pipe (8) and the condenser (2) -heat exchange type accumulator (5) And a pilot heat exchanger (9), and the temperature of the temperature-sensing automatic expansion valve (3) is sensed. (3a) is a refrigeration apparatus which is characterized in that it is arranged on the outlet side of the pilot heat exchangers of the oil return pipe (8) (9). 2. The refrigerating apparatus according to claim 1, wherein the evaporator (4) is a full liquid evaporator. 3. The refrigeration system according to claim 1 or 2, wherein the pilot heat exchanger (9) comprises an oil return pipe (8) and an electric heater for heating the oil return pipe (8). Refrigerating device. 4. The refrigerating apparatus according to claim 1, wherein a plurality of evaporators (4a) to (4c) are provided between the automatic expansion valve (3) and the heat exchange type accumulator (5). A refrigerating apparatus which is connected in parallel.